An outphasing amplifier with a non-isolating combiner is an amplifier circuit that can provide substantially high power efficiency over a wide input range. The power efficiency is a measure of the power needed to operate the amplifier for amplifying an input signal to a specific output level. However, the efficiency of such amplifier circuit drops quickly in the low input power region, where considerable power is needed to amplify relatively low input power signals. This can reduce the overall efficiency for amplifying a modulated waveform with a large peak to average power ratio. There is a need for an improved architecture for the outphasing amplifier with a non-isolating combiner that overcomes such issue to improve overall power efficiency of the system.